Related message on the comments list:
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2006Jul/0001.html
(I couldn't find any text to quote to answer the comment)
Andy
Fred Zemke wrote:
>
>
>
> 11.2 Filter evaluation
> The rules do not say how to handle an unbound variable
> in an expression. Clearly it must be possible
> for the argument of BOUND to be unbound. I believe the desired
> semantics are that it is an error to have an unbound argument
> for any other function. This should be stated explicitly.
> Also, note that the first bullet says
> "SPARQL functions do not process node sequences. When interpreting
> the semantics of XPath functions assume that each argument is
> a sequence of a single node". Given that an argument might be
> unbound, it is not true that arguments are always a sequence
> of length 1; I think the truth is that the argument may be a
> sequence of length 0 or 1.
>
> Fred
>